1. Field of the Invention
The present invention relates to polymer polyol, and flame retardant polyurethane resin and flame retardant polyurethane foam which are prepared from the same.
Polymer polyol of the invention is a graft copolymer in polyol, which can be prepared by polymerizing the specific vinyl monomers in polyol to disperse microparticles of the resulting vinyl polymer in the polyol, and is very useful for flame retadant polyurethane resin and foam.
2. Prior Art of the Invention
Polyol which is obtained by polymerizing styrene, acrylonitrile or other vinyl monomers in the polyol and contains dispersed polymer microparticles has been conventionally called polymer polyol, polymer dispersed polyol or graft copolymer in polyol (hereinafter referred to as polymer dispersed polyol) and has been used for preparation of polyurethane foam and polyurethane elastomer.
Particularly when polymer dispersed polyol is used for preparing flexible polyurethane foam, effects such as increase in open cell content and improvement in indentation hardness can be obtained on the resultant foam.
As to the preparation method of flame retardant polyurethane, it has been conventionally known to disperse melamine in polyol as a flame retardant or to add tris(2-chloroethyl) phosphate, tris(.beta.-chloropropyl) phosphate and other halogen containing flame retardants.
However, addition of these flame retardants leads to problems, for example, properties of polyurethane lower remarkably, melamine has markedly poor dispersion stability in polyol compared with a conventional polymer dispersed polyol, halogen containing flame retardants cause fogging in automobile application or generate halogen containing gas and other hazardous materials in case of combustion and is unfavorable in view of environmental protection.
On the other hand, conventional polymer polyol has a problem of no effect on flame retardance of polyurethane, and actually impairs flame retardance of polyurethane.
As to polymer dispersed polyol which exhibits effect on flame retardance of polyurethane, Japanese Patent Publication 2527006 has disclosed polymer dispersed polyol obtained by dispersing aldehyde condensate base resin microparticles, or other polymer dispersed polyol is also known to be obtained by polymerizing a halogen containing monomer in polyol.
However, according to the trace examination by the inventors of the invention, the aldehyde condensate based resin microparticles dispersed in polyol lead to impairing of polyurethane properties such as humid aged compression set which effects the durability of polyurethane in particular. Polymer dispersed polyol prepared from a halogen containing monomer is environmentally unfavorable due to the presence of halogen.
On the other hand, Japanese Laid-Open Patent SHO 51-73588 has disclosed a preparation process of a polymer-polyol composition comprising conducting radical copolymerization of one or more compounds selected from acrylonitrile and methacrylonitrile with one or more compounds selected from acrylamide and methacrylamide, and a preparation process of polyurethane by using the same. The patent has taught that viscosity of polymer dispersed polyol can be reduced by copolymerization of (meth)acrylonitrile and (meth)acrylamide.
Further, U.S. Pat. Nos. 4,503,207 and 4,555,527 have disclosed a preparation process of polymer dispersed polyol comprising conducting radical polymerization of acrylamide or methacrylamide in polyol in the presence of water and polyol having a polymerizable carbon-carbon double bond, that is, a so-called dispersion stabilizer, and polyurethane foam and elastomer obtained by using the same. These patents have taught that the polymer dispersed polyol obtained by using acrylamide in the presence of a dispersion stabilizer can reduce viscosity by micro dispersion of polymer particles. However, no description has been found at all on the flame retardant effect of the polymer dispersed polyol for polyurethane.
The examination conducted by the inventors has revealed that polymer dispersed polyol prepared by dispersing the above polyacrylamide or a polymer obtained from (meth)acrylamide and (meth)acrylonitrile in polyol can also exert flame retardance to some extent in some cases. However, polyurethane prepared from such polymer dispersed polyol greatly impairs durability, humid aged compression set in particular. Furthermore, the resin component obtained by mixing polymer dispersed polyol, water as a blowing agent, catalyst and cell regulator in polyurethane preparation has extremely poor storage stability required for practical application and thus the object of the present invention cannot be attained.
The object of the invention is to provide polymer dispersed polyol which has an effect as a raw material of flame retardant polyurethane having excellent humid aged compression set and other durability, the preparation process of the same, and flame retardant polyurethane resin and flame retardant polyurethane foam which are prepared from the same.
Another object of the invention is to provide polyurethane foam which passes FWVSS 302, has self-extinguishing property in accordance with JIS D-1201, a test method of combustion quality of organic materials for automobile interiors, has an oxygen index of 18 or more and a humid aged compression set of 20% or less; and polyurethane resin which has an oxygen index of 18 or more and a humid aged compression set of 10% or less.